Electron / Positron Injector Linac
StatusKazuro Furukawa<kazuro.furukawa@kek.jp>

for Linac division

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

Linac Overview

Mission of electron/positron Injector in SuperKEKBu 40-times higher LuminosityvTwice larger storage beam Higher beam current at Linacv20-times higher collision rate with nano-beam scheme³  Low-emittance even at first turn³  Shorter storage lifetimeuLinac challengesvLow emittance e- Low-emittance beam from Linac( Higher Linac beam current)

40xLuminosity³ with high-charge RF-gunvLow emittance e+³ with damping ringvHigher e+ beam current

e+ efficiency³ with new capture sectionvEmittance preservation³ with precise beam controlv4+1 ring simultaneous injection
Linac Upgrade Status towards SuperKEKB

2x beamcurrent

RF-gunK.Furukawa, KEK, Mar.2013.

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Linac Facility

Facility Upgrade

Ohsawa et al.
u Addition of electric power and cooling water is crucial for the upgradev However, the facility division starts the design only after the budget is securedv It was only approved in JFY2012 (the facility budget is different from the project one)u Basic schedulev Design JFY2012, Building JFY2013, Facility JFY2014v Should not affect PF and PF-AR operationv Not available during initial commissioning
high currentgun	
low emittanceRF gun	
3.5 GeV
10nC x 2 (prim. e-)
5nC x 2 (inj. e-)	Bunch
Compressor	

S-bandlinac	

e+ target &capture section	
Positron capture section
920 kVA, 900 lit/min

Linac Upgrade Status towards SuperKEKB

1.1 GeV
Damping Ringcirc. 136 m	
Energy-spread
Compression System	
3TRF gun	

50 Hz (e+ or e-)pulse-by-pulse
mode switching 	

PF
2.5 GeV e0.1nC x 1	LERPF-AR
6.5 GeV e- 	

4.0 GeV e+ 4nC x 2	ECS	C-bandmodules	

Damping ring BT (LTR, RTL)
310 kVAHER 7.0 GeV e5nC x 2	Switch yard (3SY)
300 kVA, 460 lit/min

K.Furukawa, KEK, Mar.2013.

3

Girder Recovery and Alignmentu Re-constructing soft-structure girder into hard-structureu Alignment with

Higo et al.

v 120m and 480m long-baseline laser between girdersv Laser tracker within a girder (~20m)v Beam-based testsv Target: 0.1mm local / 0.3mm global alignment (from beam dynamics simulation)³ Several iterations necessary for low-emittance beam transportu Beam transport/acceleration test for 600m (Nov.2012)v For the first time after the earthquake

XYCharge
Girder Distortion

Girder Reinforcement

Linac Upgrade Status towards SuperKEKB

Beam along 600-m linac
K.Furukawa, KEK, Mar.2013.

4

Microwave Power Source UpgradeuPulsed power modulators

Michizono et al.

vNine compact modulators are introducedvShare the same basic design for klystron, flux
concentrator, and gun high voltageuFast LLRF controllers, power amplifiers, andLLRF monitorsvFor simultaneous injection and bucket selectionvPulse-to-pulse stability monitorv50Hz event-based synchronized controls

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

5

RF Gun for Low-emittance Electron Beam

RF Gun Development

Yoshida et al.

u Photo cathode : stability, longer life, efficiency

Ir5CevAt first LaB6, then Ir5Ce  5nC / bunchu Laser : higher power, temporal profile controlvNd:YAG medium, LD excitation  ~1.5mJ / 30ps / pulse at 266nmvPolarization control for slant irradiationvYb:YAG fiber laser is introducedu Cavity : better focusing field, higher gradientv DAW (Disk and washer) type cavity

DAWvDevelopment of quasi-travelling-wave side-coupled cavity as wellu Test standsv RFgun at A-1 is constructed with fiber laser for SuperKEKBv RFgun at 3-2 was used to inject into PF with proper synchronizationv Long-period demonstration will be performed
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

6Beam Acceleration Test (RF-gun)uStep-by-step beam testsv4.5nC 240m accelerationvFiber-laser-based RF-gunXYCharge
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

7

Positron Capture for High-current Positron

Positron Capture Section Developmentu Flux concentrator (FC)

Kamitani et al.

v Collaborations with BINP, IHEP and SLACv Finalized optimization of field and mechanical designv Fabricated 1st version of 2nd generation, being testedu Large-aperture S-band (LAS) cavity structurev Positron capture tracking simulation

FCv L-band structure as backup with co-linear loadu Magnet design and fabricationv Solenoid and pulsed steering and quad magnet systemu Reliabilityv Strategy for failed component replacementwith detachable girder, etcLASv Acceleration gradient distribution andoptimization with backups
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

8

Beam Monitors: BPM and WS Suwada et al.
³ Limited performance with present 8-bit 10GS/s digitizers (oscilloscopes)u New BPM readout for precise orbit/emittance controlsvFast attenuator for 0.1-10nC (SuperKEKB, PF, PFAR) dynamic rangevHelical BSF (300MHz) for 2-bunch (96ns apart) readoutv16bit 250MS/s ADC, FPGA data processing BPM(18K12)
AD
ADC"ch.(1LSB=0.038mV)
v50Hz event-control synchronization(2012/2/7,")

60000"
50000"

1.8V
40000"
CH1"
30000"
20000"
10000"
0"200"

100ns
220"

240"

260"

280"

300" x"4nsuNew wire scanner readout was also developed
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013.

9

Dual-layer Controls

Single Machine, Multiple Virtual Accelerators (VAs)u Simultaneous injection, one of the VAs is active at a timeu Independent parameter set for each VA, ~200 parameters are switchedevery 20ms pulsee− Gun
ARCPF Injectione– (2.5GeV)

e− GunKEKB-LER Injection

ARCEvent-basedControl System

Primary e– (3.5GeV)

e+ (4GeV)

e+ Targete− GunARC

KEKB-HER Injectione– (7GeV)e− GunARC

Linac Upgrade Status towards SuperKEKB

PF-AR Injectione– (6.5GeV)

K.Furukawa, KEK, Mar.2013. 10

Dual-layer Controls

Example of Beam Mode Pattern : e+ 25Hz / e– 25Hzu Interleaved e+ and e-, dependency between pulses mostly decoupledu With bucket selection at the both DR and MR
e− GunARC
Primary e– (3.5GeV)

e+ (4GeV)

e+ Target

20ms

e− GunARCe– (7GeV)
20ms
e− GunARC
Primary e– (3.5GeV)

e+ (4GeV)

e+ Target

20ms

e− GunARCe– (7GeV)
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 11

u Preliminary Beam Tests in Autumn 2012v Beam test along 600-m Linacv for the first time after the earthquakev Latter half was tuned for PF/PFAR injectionv Alignment will be recovered by 2014

XYChargev For energy spread optimizationv Longitudinal beam profile managementby photo-cathode RF-gun (30ps square shape)v and bunch compression at the middle of linac
are crucial

Beam along 600-m linac
R56=0³ Preliminary R56 control
was performed³ Design and measurementof dispersion function
with R56=0 and R56=-0.6

R56=-0.6
DesignLinac Upgrade Status towards SuperKEKB

Measurement
K.Furukawa, KEK, Mar.2013. 12

Schedule

Scheduleu Winter 2013 : DR switchyard / DR tunnel constructionu Spring 2013 : A1-RF-gun, Alignmentu Summer 2013 : Installation of many componentsv ECS, FC (gen.2), DC solenoids, Klystron modulators, WS, etcu Autumn 2013 : e– then e+ commissioning (limited current)vHalf Linac: PF injection, Day: construction, Night: commissioningu Spring 2014 : Pulsed steering, Alignmentu Summer 2014 : Installation of additional componentsv Cooling water, FC (gen.3), BPM, Pulsed magnets, New PFAR BT, etcu Autumn 2014 : Linac Full Commissioningu Winter 2015 : MR (then DR) injection commissioningu …
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 13

Summaryu Much progress in disaster recovery and constructionu Development for T=0 (~1nC) was mostly completedu Development for full spec. will be testedu Many development items are connected with beam emittance andenergy spread managementu Still expecting many challenging items to overcomeu Injector should start at first !
u With some Phronesis (Greek: practical wisdom, ability tounderstand the universal truth), we believe we can achieve thetarget

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 14

Thank you

Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 15

Review 2013 and Reviewer’s Comments (preliminary)u Overview of Injector Construction Status and Schedulev The Linac Group setup prioritized work scopes with back-up options. The overall
scheme is very logical, and the committee is convinced by their near term plan.

u RF gunv Install and test the QTWSC gun as planned. Operate it for a long period to check its
reliability and performance stability.

u Alignment and Supportv The Linac alignment and support is less mature. There should be some effort toaccelerate this to avoid the possibility of impacting commissioning.

u Positron Sourcev The target size should fit into the available space between the yoke and flux
concentrator. The discharge waveform of the modulator for the flux concentrator withcables should be checked experimentally.

u Commissioning (of Electron Beam)v After identifying the parameters that the linac electron beam needs to meet, a detailed
set of procedures should be made for each parameter. An overall time schedule to carryout these procedures should be developed to match times needed by the four rings.
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 16

Review Items in 2012 and Reviewer’s Commentsu Linac disaster recoveryvEarthquake is a natural disaster, a Force Majeure. In view of themanpower shortage in the Linac and Storage Ring groups, thecommittee suggests that the management team look into timeline,
milestones and resources, and revise the schedule accordingly.

u RF gun and low-emittance transportvAggressively pursue a demonstration of the QTW gun with LaB6
cathode and the full power laser.

u Positron sourcevCSR effects in the bunch compressor should be examined. Aprotection scheme for the target should be developed at least
conceptually.
Linac Upgrade Status towards SuperKEKB

K.Furukawa, KEK, Mar.2013. 17

Linac Overview

Linac Upgrade for SuperKEKB
u Higher Injection Beam Currentv To Meet the larger stored beam current and shorter beam lifetime in the ringv 4~8-times larger bunch current for electron and positronu Lower-emittance Injection Beamv To meet nano-beam scheme in the ringv Positron with a damping ring, Electron with a photo-cathode RF gunv Emittance preservation by alignment and beam instrumentationu Quasi-simultaneous injections into 4 storage ringsv SuperKEKB e–/e+ rings, and light sources of PF and PF-ARv Improvements to beam instrumentation, low-level RF, controls, timing, etc
SuperKEKB injector Linac	

high currentgun	
low emittanceRF gun	

3.5 GeV
10nC x 2 (prim. e-)
5nC x 2 (inj. e-)	Bunch
Compressor	

S-bandlinac	

e+ target &capture section	
Linac Upgrade Status towards SuperKEKB

1.1 GeV
Damping Ringcirc. 136 m	
Energy-spread
Compression System	
3TRF gun	

50 Hz (e+ or e-)pulse-by-pulse
mode switching 	PF
2.5 GeV e0.1nC x 1	LERPF-AR
6.5 GeV e- 	

4.0 GeV e+ 4nC x 2	ECS	C-bandmodules	

HER 7.0 GeV e5nC x 2	K.Furukawa, KEK, Mar.2013. 18

Linac Upgrade for SuperKEKB
PFB
J-arc
1.5 GeVA

Primary e– for e+
3.2 GeV, 10nC x 2
BunchCompression

C1

Bunch
Compression

New e+Capture
with FC

2

2.5 GeV
0.1nC x 1

1.1 GeV
e+ damping ring

New RF-gun
5 nC for e–, 10nC for e+
IrCe cathode, Fiberlaser, DAW cavity

SY2

EnergyCompression

3Energy

SY3 Compression

45PF-AR
6.5 GeV
5nCLER4.0 GeV e+
4nC x 2HER

7.0 GeV
5nC x 220 umu As a high-field (several Tesla) pulsed solenoid for the positron source of theSuperKEKB injector, KEK is going to fabricate a SLAC-type flux concentrator.
u Technical advices from the IHEP experts and design information by the IHEP
drawings are quite useful in the development.

FluxConcentrator

electronbeam

Linac Upgrade Status towards SuperKEKB

positronbeamK.Furukawa, KEK, Mar.2013.